The present invention relates to measuring devices and, more particularly, to apparatus for measuring a number of particles and an amount of pigment in a test liquid.
To measure the number and the size of blood components (leukocytes, corpuscles, etc.) in a blood sample, the prior art mixes the blood sample with an electrically conducting liquid (an electrolyte), and passes a fixed volume of the mixture through a minute hole. Electrodes on opposed sides of the minute hole pass an electric current through the mixture, and particularly through the hole. The electrical resistance of blood components is different from that of the electrolyte. As a result, when a particle of blood component passes through the minute hole, it partly blocks the minute hole, thereby changing the electrical resistance therethrough. A resulting pulse change in resistance is detected. The pulses are counted while the fixed quantity of the mixture is drawn through the minute hole to indicate the amount of blood component particles in the mixture. The amount of hemoglobin (red pigment) in the mixture is measured with a colorimeter.
When the number of leukocytes and the amount of hemoglobin are measured by conventional apparatus using a test mixture containing hemolyzed red blood corpuscles, two separate liquid routes are required: one for measuring the number of leukocytes, the other for measuring the amount of hemoglobin.
Therefore, the liquid routes of conventional devices are complicated and expensive. Conventional devices also require large amounts of test mixture and a large amount of liquid for cleanup between tests.
In addition, conventional fluid control systems and devices controlling operation of fluid circuits, as well as devices for moving various parts of control systems, are bulky and inconvenient. Elements of such control systems frequently use tubes.
Furthermore, testing of blood components is frequently done in a series of tests of different blood samples. Purging of the equipment between tests is required in preparation for the next test. An automated technique for performing the tests and for performing the cleanup is desirable.